1. Field of the Invention
The present invention relates to a perpendicular magnetic recording head for recording data on a recording medium, such as a disk having a hard surface, under application of a perpendicular magnetic field. More particularly, the present invention relates to a perpendicular magnetic recording head and a method of manufacturing the head, which can suppress the occurrence of fringing in a recording pattern, can form a main magnetic pole layer with high pattern accuracy and form a yoke surface having a large film thickness, and can improve the passing efficiency of magnetic flux.
2. Description of the Related Art
Conventionally, a perpendicular magnetic recording method is utilized in a device for recording magnetic data on a recording medium, such as a disk, with a high density. FIG. 38 is a sectional view showing a general structure of a perpendicular magnetic recording head for use in the known perpendicular magnetic recording device.
As shown in FIG. 38, a perpendicular magnetic recording head H utilizing the perpendicular magnetic recording method is provided on a side end surface of a slider 1 moving or sliding in a floating relation over a recording medium. On a side end surface 1a of the slider 1, for example, the perpendicular magnetic recording head H is disposed between a nonmagnetic film 2 and a nonmagnetic coating film 3.
The perpendicular magnetic recording head H has an auxiliary magnetic pole layer 4 made of ferromagnetic materials, and a main magnetic pole layer 5 also made of ferromagnetic materials and formed above the auxiliary magnetic pole layer 4 with a space left between both the layers. An end surface 4a of the auxiliary magnetic pole layer 4 and an end surface 5a of the main magnetic pole layer 5 appear at an opposing surface Ha of the head positioned opposite to a recording medium M. The auxiliary magnetic pole layer 4 and the main magnetic pole layer 5 are magnetically coupled to each other in a magnetic coupling portion 6 located inward of the opposing surface Ha.
A nonmagnetic insulating layer 7 made of inorganic materials, such as Al2O3 and SiO2, is positioned between the auxiliary magnetic pole layer 4 and the main magnetic pole layer 5. In the opposing surface Ha, an end surface 7a of the nonmagnetic insulating layer 7 appears between the end surface 4a of the auxiliary magnetic pole layer 4 and the end surface 5a of the main magnetic pole layer 5.
Then, a coil layer 8 made of conductive materials, e.g., Cu, is embedded in the nonmagnetic insulating layer 7.
Also, as shown in FIG. 38, the end surface 5a of the main magnetic pole layer 5 has a thickness hw smaller than a thickness hr of the end surface 4a of the auxiliary magnetic pole layer 4. A width size of the end surface 5a of the main magnetic pole layer 5 in the direction of track width (indicated by X in FIG. 38) defines a track width Tw that is much smaller than a width size of the end surface 4a of the auxiliary magnetic pole layer 4 in the direction of track width.
The recording medium M, on which magnetic data is to be recorded by the perpendicular magnetic recording head H, is moved in the Z-direction relative to the perpendicular magnetic recording head H. The recording medium M has a hard surface Ma on the outer surface side and a soft surface Mb on the inner side.
When a recording magnetic field is induced in both the auxiliary magnetic pole layer 4 and the main magnetic pole layer 5 upon energization of the coil layer 8, a leaked recording magnetic field passes between the end surface 4a of the auxiliary magnetic pole layer 4 and the end surface 5a of the main magnetic pole layer 5 while perpendicularly penetrating the hard surface Ma of the recording medium M and propagating in the soft surface Mb. Since the end surface 5a of the main magnetic pole layer 5 has an area much smaller than that of the end surface 4a of the auxiliary magnetic pole layer 4 as described above, magnetic flux "PHgr" is concentrated on a portion of the recording medium opposing to the end surface 5a of the main magnetic pole layer 5. Thus, magnetic data is recorded in a portion of the hard surface Ma opposing to the end surface 5a with the concentrated magnetic flux "PHgr".
However, the conventional perpendicular magnetic recording head H, shown in FIG. 38, has the following problems.
(1) In the structure shown in FIG. 38, an upper surface of the nonmagnetic insulating layer 7 has a certain degree of roughness, and therefore the main magnetic pole layer 5 formed on the upper surface of the nonmagnetic insulating layer 7 has reduced pattern accuracy. On the other hand, it is particularly required not only to reduce the area of the end surface 5a of the main magnetic pole layer 5, which appears at the opposing surface Ha, so that the leaked recording magnetic field is highly concentrated, but also to narrow the track width Tw defined by the end surface 5a for achieving a high recording density on the recording medium M.
Accordingly, the structure shown in FIG. 38 causes a difficulty in forming the end surface 5a of the main magnetic pole layer 5 so as to provide a smaller track width Tw and hence a narrower track with high pattern accuracy. Thus, the conventional structure is not satisfactorily adaptable for a higher recording density.
(2) In order to introduce, to the opposing surface Ha, a magnetic field induced from the coil layer 8, an inward area of the main magnetic pole layer 5 is required to have a larger cross-sectional area through which the magnetic flux is allowed to pass. In the structure shown in FIG. 38, however, the main magnetic pole layer 5 is formed to extend rearward in the height direction (indicated by Y in FIG. 38) with a substantially constant film thickness, and the film thickness of the main magnetic pole layer 5 cannot be increased in the inward area thereof. Hence, the magnetic field induced from the coil layer 8 cannot be effectively introduced to a fore end of the main magnetic pole layer 5.
(3) Since the main magnetic pole layer 5 is formed as a single layer in the structure shown in FIG. 38, it is difficult to extremely reduce only the track width Tw defined by the end surface 5a of the main magnetic pole layer 5. Stated otherwise, the main magnetic pole layer 5 is formed by forming a holed pattern on a resist layer and then applying a magnetic material to the holed pattern by, e.g., plating. Such a process has a difficulty in extremely reducing the width size of the holed pattern only in a portion where the end surface 5a is to be formed.
(4) When the slider 1 is moved between an outer periphery and an inner periphery of the recording medium M in the form of a disk, the end surface 5a of the main magnetic pole layer 5 is sometimes inclined and causes a skew angle with respect to the tangential direction of rotation of the recording medium M (i.e., the Z-direction in FIG. 38). In the case of the end surface 5a of the main magnetic pole layer 5 being square or rectangular as shown in FIG. 39, if the end surface 5a of the main magnetic pole layer 5 has a skew angle with respect to the tangential direction of rotation of the recording medium (i.e., the Z-direction in FIG. 38), a lateral side 5b of the main magnetic pole layer 5 provides an inclined leaked magnetic field within a track width Tw1, as indicated by a broken line, whereby fringing F occurs and off-track characteristics deteriorate.
With the view of overcoming the above-mentioned problems in the related art, it is an object of the present invention to provide a perpendicular magnetic recording head and a method of manufacturing the head, which can form an end surface of a main magnetic pole layer with higher pattern accuracy, and which is adaptable for a narrower track.
Another object of the present invention is to provide a perpendicular magnetic recording head and a method of manufacturing the head, which can substantially increase an effective film thickness of the main magnetic pole layer in an inward area thereof, and which can more efficiently introduce magnetic flux, induced from a coil layer, to the end surface of the main magnetic pole layer.
Still another object of the present invention is to provide a perpendicular magnetic recording head and a method of manufacturing the head, which can suppress the occurrence of fringing in a recording pattern, and which can improve off-track characteristics.
To achieve the objects, the present invention provides a perpendicular magnetic recording head comprising an auxiliary magnetic pole layer, an insulating layer formed on the auxiliary magnetic pole layer, and a main magnetic pole layer formed on the insulating layer, wherein magnetic data is recorded on a recording medium by a perpendicular magnetic field concentrated on the main magnetic pole layer when a recording magnetic field is applied to the auxiliary magnetic pole layer and the main magnetic pole layer from a coil layer embedded in the insulating layer; the main magnetic pole layer is formed on a high-flatness surface and has a front end surface positioned in an opposing surface of the head opposite to the recording medium, the front end surface being formed in a shape with a width size gradually increasing in a direction of track width as the front end surface departs farther away from the auxiliary magnetic pole layer, the front end surface having an upper edge, of which width size in the direction of track width is defined at a track width Tw; and a yoke layer is formed in a larger film thickness than the main magnetic pole layer and has a cross-sectional area in a cross-section cut parallel to the opposing surface larger than an area of the front end surface of the main magnetic pole layer, the yoke layer having a front end surface positioned inward of the opposing surface and being magnetically coupled to the main magnetic pole layer.
With those features of the present invention, the main magnetic pole layer is formed on the insulating layer flattened into a high-flatness surface. Therefore, the main magnetic pole layer can be formed with high pattern accuracy. In particular, the front end surface of the main magnetic pole layer can be formed to be satisfactorily adapted for a narrower track.
Also, the front end surface of the main magnetic pole layer is formed in a shape with a width size gradually increasing in a direction of track width as the front end surface departs farther away from the auxiliary magnetic pole layer. It is therefore possible to satisfactorily prevent the occurrence of fringing in a recording pattern and to improve off-track characteristics.
Further, the yoke layer having a larger film thickness than the main magnetic pole layer is magnetically coupled to the main magnetic pole layer. It is therefore possible to effectively introduce magnetic flux from the yoke layer to the main magnetic pole layer, to increase the passing efficiency of the magnetic flux, and to improve overwrite characteristics.
The present invention can provide the perpendicular magnetic recording head having preferred structures as follows.
In one preferred structure of the present invention, a connecting layer rising from the auxiliary magnetic pole layer is formed inward of the opposing surface; the main magnetic pole layer is formed on the insulating layer flattened into a high-flatness surface, and the yoke layer is formed to lie on the main magnetic pole layer; and a base end portion of the main magnetic pole layer or a base end portion of the yoke layer is magnetically coupled to the connecting layer. That structure corresponds to FIG. 1.
In another preferred structure of the present invention, a second insulating layer is formed around the main magnetic pole layer, an upper surface of the second insulating layer and an upper surface of the main magnetic pole layer are formed on a same plane, and the yoke layer is formed on the same plane. That structure corresponds to FIGS. 11 and 12.
In the present invention, preferably, an upper surface of the main magnetic pole layer is covered by a third insulating layer except for the base end portion of the main magnetic pole layer, and the yoke layer is magnetically connected to the base end portion of the main magnetic pole layer. That structure corresponds to FIG. 5.
In still another preferred structure of the present invention, a connecting layer rising from the auxiliary magnetic pole layer is formed inward of the opposing surface; the main magnetic pole layer is formed on the insulating layer flattened into a high-flatness surface, and has a base end portion positioned nearer to the opposing surface than the connecting layer; and the yoke layer is also formed on the insulating layer and has a front end surface magnetically coupled to a rear end surface of the main magnetic pole layer, the yoke layer having a base end portion magnetically coupled to the connecting layer. That structure corresponds to FIG. 2.
In still another preferred structure of the present invention, a connecting layer rising from the auxiliary magnetic pole layer is formed inward of the opposing surface; the yoke layer is formed on the insulating layer flattened into a high-flatness surface and has a base end portion magnetically coupled to the connecting layer, and a fourth insulating layer is formed between the front end surface of the yoke layer and the opposing surface, an upper surface of the fourth insulating layer and an upper surface of the yoke layer being flattened flush with each other; and the main magnetic pole layer is formed to lie on the high-flatness upper surface of the yoke layer. That structure corresponds to FIGS. 3 and 4.
In still another preferred structure of the present invention, a connecting layer rising from the auxiliary magnetic pole layer is formed inward of the opposing surface, and a magnetic material layer is formed on the insulating layer flattened into a high-flatness surface, the magnetic material layer comprising a front area formed in a predetermined length to extend in a height direction from the opposing surface, and a rear area formed to extend rearward from a base end of the front area in the height direction, the rear area having a base end portion being magnetically coupled to the connecting layer; and the front area has a smaller film thickness than the rear area, the front area serving as the main magnetic pole layer, the rear area serving as the yoke layer. That structure corresponds to FIG. 6.
In the present invention, preferably, the front end surface of the yoke layer laid on or under the main magnetic pole layer is formed as a sloped or curved surface that is inclined in a height direction as the front end surface departs farther away from the main magnetic pole layer.
In the present invention, preferably, opposite lateral sides of the front end surface of the main magnetic pole layer in the direction of track width are formed as sloped or curved edges.
Further, the present invention provides a method of manufacturing a perpendicular magnetic recording head, the method comprising the steps of (a) forming an auxiliary magnetic pole layer of a magnetic material; (b) forming a connecting layer on the auxiliary magnetic pole layer at a position inward of an opposing surface of the head opposite to a recording medium, forming a coil layer on the auxiliary magnetic pole layer through an insulating undercoat layer over an area between the opposing surface and the connecting layer, and then filling an insulating layer on the coil layer; (c) polishing a surface of the insulating layer such that an upper surface of the insulating layer and an upper surface of the connecting layer are flattened flush with each other; (d) forming a resist layer on the insulating layer and the connecting layer, and forming in the resist layer a holed pattern having a hole space, of which inner width size in a direction of track width in at least the opposing surface gradually increases as the hole space departs farther away from the auxiliary magnetic pole layer; (e) forming a main magnetic pole layer in the holed pattern by plating, and removing the resist layer; and (f) forming a resist layer having a larger film thickness than the main magnetic pole layer to overlie from the main magnetic pole layer to the insulating layer, forming in the resist layer a holed pattern for a yoke layer, the holed pattern having a front end surface positioned inward of the opposing surface, the holed pattern being positioned on the main magnetic pole layer or on the insulating layer in an area extending from a rear end surface of the main magnetic pole layer in a height direction, forming the yoke layer in the holed pattern by plating, and then removing the resist layer.
With the manufacturing method set forth above, the perpendicular magnetic recording head shown in FIG. 1 or 2 can be manufactured.
In the manufacturing method of the present invention, the step (f) may be replaced by the steps of (g) forming a second insulating layer around the main magnetic pole layer, and flattening an upper surface of the insulating layer and an upper surface of the main magnetic pole layer to be flush with each other; and (h) forming a resist layer having a larger film thickness than the main magnetic pole layer to overlie from the main magnetic pole layer to the second insulating layer, forming in the resist layer a holed pattern for a yoke layer, the holed pattern having a front end surface positioned inward of the opposing surface, the holed pattern being positioned on the main magnetic pole layer and the second insulating layer, forming the yoke layer in the holed pattern by plating, and then removing the resist layer.
With the manufacturing method set forth above, the perpendicular magnetic recording head shown in FIGS. 11 and 12 can be manufactured.
In the manufacturing method of the present invention, the step (f) may be replaced by the steps of (i) forming a third insulating layer to overlie from the main magnetic pole layer to the insulating layer; (j) forming a hole in an area of the third insulating layer formed at least on a base end portion of the main magnetic pole layer; and (k) forming a resist layer having a larger film thickness than the main magnetic pole layer to lie on the third insulating layer, forming a holed pattern for a yoke layer in the resist layer, the holed pattern having a front end surface positioned inward of the opposing surface, forming the yoke layer in the holed pattern by plating, and then removing the resist layer.
With the manufacturing method set forth above, the perpendicular magnetic recording head shown in FIG. 5 can be manufactured.
In the manufacturing method of the present invention, the steps (d) to (f) are replaced by the steps of (1) forming a resist layer on the insulating layer, forming a holed pattern for a yoke layer in the resist layer, the holed pattern having a front end surface positioned inward of the opposing surface, forming the yoke layer in the holed pattern by plating, and then removing the resist layer; (m) forming a fourth insulating layer to lie on the yoke layer and the insulating layer, and polishing the fourth insulating layer such that an upper surface of the fourth insulating layer and an upper surface of the yoke layer are flattened flush with each other; and (n) forming a resist layer having a smaller film thickness than the yoke layer to lie on the yoke layer and the fourth insulating layer, and forming a holed pattern for the main magnetic pole layer to extend from an area of the resist layer on the fourth insulating layer, which is positioned on the side nearer to the opposing surface than a front end surface of the yoke layer, to an area of the resist layer on the yoke layer; and (o) forming the main magnetic pole layer in the holed pattern by plating, and then removing the resist layer.
With the manufacturing method set forth above, the perpendicular magnetic recording head shown in FIG. 3 or 4 can be manufactured.
In the manufacturing method of the present invention, the steps (d) to (f) are replaced by the steps of (p) forming a resist layer on the insulating layer and the connecting layer, and forming in the resist layer a holed pattern having a hole space, of which inner width size in a direction of track width in at least the opposing surface gradually increases as the hole space departs farther away from the auxiliary magnetic pole layer, the holed pattern having a base end portion formed to extend over the connecting layer; (q) forming a magnetic material layer in the holed pattern by plating, and then removing the resist layer; and (r) forming a resist layer on the magnetic material layer, forming in the resist layer a holed pattern through exposure and development processes, the holed pattern having a hole space positioned on the main magnetic material layer over a predetermined distance from the opposing surface in a height direction, and removing a part of the magnetic material layer, which is exposed through the hole space of the holed pattern, to have a reduced film thickness, the part of the magnetic material layer serving as the main magnetic pole layer, a remaining part of the magnetic material layer formed under the resist layer serving as the yoke layer.
With the manufacturing method set forth above, the perpendicular magnetic recording head shown in FIG. 6 can be manufactured.